Fabrication of CoFe/N-doped mesoporous carbon hybrids from Prussian blue analogous as high performance cathodes for lithium-sulfur batteries

CoFe/N-doped mesoporous carbon hybrids are synthesized by a simple pyrolysis of Prussian blue analogue (PBA) and melamine, in which the structure is rationally designed by controlling the weight ratio of PBA/melamine and annealing temperature. By applying the composite as the cathode material for lithium-sulfur batteries, it demonstrates outstanding electrochemical performances including a high reversible capacity (1315 mAh g(-1) at 0.2 C), excellent rate capability (724 and 496 mAh g(-1) at 2 and 5 C rates, respectively) and superior cycling stability (528 and 367 mAh g(-1) at 2 and 5C after 500 cycles, respectively). The synergetic effect of the mesoporous carbon matrix, uniform sized CoFe nanoparticles and N heteroatoms simultaneously contributes to the confinement of sulfur species. The presence of abundant mesopores and micropores can physically confine sulfur species. The formed CoFe-N-x moieties can not only improve the electronic conductivity of the as-prepared composites, but also offer highly effective active sites for chemical absorption and catalytic transformation of polysulfides to suppress any shuttle effect. In addition, the mesoporous structure can effectively alleviate the volume changes resulted from charge-discharge process. The strategy developed in this work proposes an alternative way to obtain N-doped mesoporous carbon matrix modified with CoFe nanoparticles for high performance cathode materials of lithium-sulfur batteries. (C) 2019 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.